Search NASA⌕ Search

Engineering topics

Atkins, H.

Publications and source records attributed to Atkins, H..

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Nonreflective boundary conditions for high-order methods

A different approach to nonreflective boundary conditions for the Euler equations is presented. This work is motivated by a need for inflow and outflow boundary conditions that do not limit the useful accuracy of high-order accurate methods. The primary interest is in the propagation and convection of continuous acoustic and convective waves. This new approach employs the exact solution to finite waves to relate interior values and ambient conditions to boundary values. The method is first presented in one dimension and then generalized to multidimensions. Grid refinement studies are used to demonstrate high-order convergence for both one-dimensional and two-dimensional flows.

Atkins, H.↗
NASA NTRS1993

A comparison of two formulations for high-order accurate essentially non-oscillatory schemes

The finite-volume and finite-difference implementations of high-order accurate essentially nonoscillatory shock-capturing schemes are discussed and compared. Results obtained with fourth-order accurate algorithms based on both formulations are examined for accuracy, sensitivity to grid irregularities, resolution of waves that are oblique to the mesh, and computational efficiency. Some algorithm modifications that may be required for a given application are suggested. Conclusions that pertain to the relative merits of both formulations are drawn, and some circumstances for which each might be useful are noted.

Casper, J.↗
NASA NTRS1984

Opportunities for commercial organizations

The possible applications of technology of materials processing in low gravity is discussed. A special office established by NASA to familiarize commercial organizations with materials processing in low gravity is described. This office provides information on present research and will, if requested, hold a seminar to present the technological and business aspects of joint investigations and joint endeavors to interested organizations. Arrangements can be made for visits to laboratories where ground based research is in progress.

Vardaman, W. K.↗
NASA NTRS1976

Very-wide-field camera. Proposal of Space Astronomy Laboratory for second Spacelab mission

A proposal is made for inclusion of a very wide field camera onboard Spacelab. Its scientific program is outlined: detection and photometry, spectrography, and star and starlike object photography. The optics, receptor, and mechanical structure are described. Scientific and technical constraints are discussed, and a development plan is detailed. The dust contamination of Spacelab using the camera was also studied.

Courtes, G.↗